PDF Accessibility Checker

What an automated checker can and cannot tell you

It can tell you that a PDF has no structure tree, that no figure carries alt text, that the heading hierarchy jumps from H2 to H4, that a form field has no tooltip. Those are facts sitting in the file.

It cannot tell you whether "image1.png" is a useful description of a chart, whether the reading order makes sense to somebody who cannot see the page, or whether a heading describes what follows it. No automated tool can certify PDF/UA or WCAG conformance, and this one does not claim to. It finds the failures a machine can see, so a human audit can start from the interesting problems instead of the obvious ones.

The fourteen rules

• Tagged — /MarkInfo /Marked true and a /StructTreeRoot. Without both, assistive technology sees a stream of glyphs.
• Language — a well-formed /Lang, or a screen reader reads French with an English voice.
• Title and DisplayDocTitle — a real title, and a viewer preference telling readers to use it rather than the filename. The second is a PDF/UA requirement almost every document fails.
• Figure alt text — /Alt or /ActualText on every /Figure.
• Heading hierarchy — starts at H1, never skips a level.
• Table headers — /TH cells, ideally with /Scope or /Headers.
• Lists — real /L, /LI, /Lbl, /LBody, not paragraphs that start with a bullet character.
• Links — alternate text, a /Link element, and link text that means something out of context.
• Form fields — a /TU tooltip on every field.
• Reading order — the check most tools skip. The structure order is compared against the visual order of the same content, column by column, and every divergence is reported with its position on the page.
• Contrast — the page is rasterised and each text line is sampled. This is an approximation and is labelled as one.
• Untagged content — glyphs on the page that no structure element claims.
• Artifacts — running heads and feet that are inside the reading order instead of marked as decoration.

A rule that does not apply — no tables, no forms — is excluded from the score rather than counted as a pass. A rule that cannot be checked because the document is untagged is reported as cannot check, and earns nothing.

Privacy

The PDF is read, rendered and scored entirely in your browser. Nothing is uploaded.